KTPH to refund 200+ breast cancer patients wrongly diagnosed with aggressive HER-2 protein

In December, Khoo Teck Puat Hospital disclosed a diagnostic failure that had affected at least 200 of its breast cancer patients over nearly a decade. These patients had been told they carried the HER-2 protein, a marker that signals a more aggressive form of the disease and typically calls for targeted chemotherapy. The diagnosis was wrong. Many of them had undergone expensive treatment they did not need, spending tens of thousands of dollars out of pocket for drugs and cycles of care that offered them no medical benefit.

The error came to light through an internal safeguard. KTPH's tumour board, the committee that reviews cancer cases, noticed something unusual: the hospital was diagnosing HER-2 positive breast cancer at a rate that seemed too high. That observation triggered a comprehensive review of all HER-2 tests conducted since 2012, when the hospital first began performing the test in-house. What they found was systematic misdiagnosis stretching back years.

HER-2 testing is not straightforward. The protein appears in only 15 to 20 percent of breast cancer cases globally, making it relatively uncommon. The test itself is technically demanding—it requires a trained pathologist to interpret results, and the process involves multiple steps where human judgment matters: how the tissue sample is prepared, how the stains are applied, how the slides are handled. Globally, about 6 percent of patients receive a false positive diagnosis. But at KTPH, the rate had been far higher. The complexity of the test, combined with the number of human interventions required, created room for error to accumulate without immediate detection.

The primary drug used to treat HER-2 positive breast cancer is Herceptin, which costs between $3,000 and $4,000 per cycle in Singapore's public sector, and roughly $5,000 in private facilities. Eight of the wrongly diagnosed patients had been treated in private hospitals. For patients receiving multiple cycles of treatment, the financial toll was substantial. Beyond the direct cost of medication, there were the side effects to contend with. Herceptin commonly causes diarrhoea, chills, and fatigue. In 3 to 4 percent of patients, it can trigger heart problems—a serious risk for people who never needed the drug in the first place.

When the error was disclosed in early December, it prompted urgent questions in Parliament. Several members asked why the mistake had taken so long to surface, and whether the hospital bore responsibility for the unnecessary harm and expense. Senior Minister of State for Health Koh Poh Koon acknowledged that the complexity of HER-2 testing explained part of the delay, but he also emphasized that KTPH's internal processes had ultimately caught the problem. The tumour board's vigilance—noticing that the positive diagnosis rate was abnormally high—had been the mechanism that forced the review.

On the question of compensation, Dr. Koh announced that the hospital would fully refund all costs arising from the unnecessary treatment. He acknowledged that not all 200 wrongly diagnosed patients had actually received Herceptin; some were too frail to tolerate chemotherapy, and their diagnoses, while incorrect, had not led to treatment. But for those who had been treated, the refunds would be substantial. Even accounting for the government subsidies that some patients had received, the total bill would likely run into the millions of dollars.

Parliamentary members pressed for a broader understanding of the harm. Dr. Tan Wu Meng, himself a cancer specialist, suggested that compensation should account for more than just the direct medical costs. Patients and their caregivers had taken time away from work for appointments, infusions, and recovery. That lost income and lost time represented a real cost that money alone could not fully address. Dr. Koh did not commit to a specific formula, noting that the circumstances varied widely from patient to patient.

As of early January, KTPH was reaching out to all affected patients. The hospital's doctors were assessing them for any lingering side effects from Herceptin and other treatments they had received. Eight additional patients whose diagnoses were being reviewed remained in a state of uncertainty; their retests had not yet been completed. For the broader group of 200, the path forward involved both medical follow-up and financial reckoning—a slow process of trying to undo a mistake that had already reshaped their lives.